Hi Haldi.
Your chef did things in a similar way to the chef I watched in what used to be the Gatwick Tanoori. i.e. the addition of oil, spices (& sugar, in my case), to A SMALL initial quantity of base; then after the flavour of the spice has been extracted by the hot all, he added the remaining base and other ingredients.
I believe this technique is critical to getting the BIR taste! I've tried adding all the base first, the flavour does not develope correctly and texture ends up more gritty.
I believe that what happens is that the hot oil is in relative excess initially, which allows the oil to properly extract the (lipid soluble) flavours from the spice mix. The small amount of base prevents the spice burning, because as long as water remains boiling away in the base, the pan will not get hotter than 100 C! So in effect the initail addition of base just prevents the spice burning. I have read elsewhere on Cr0 that one contributer has seen oil AND water heated TOGETHER before the addition of spice (he even admitted that it seemed odd to to this!) - same reason!!
Whenever I use a 'curry-powder' such as the Bruce Edward's one, I ALWAYS adopt this method. The only time I do not do this is when adding cummin or garam masalla, which goes in near the end of the cooking time.
I must say, I think this site is great, I never realized that there were so many like-minded people out there!